Same difference. When you take away money that older people are living on, you force them to look for work. Which, in this economy, will tend to make them unemployed.

I suppose great-grandma can always move in with her grandkids. Of course, the grandkids are also 25% likely to be unemployed.

Naturally, there is a subset of people for whom Social Security is a needless luxury because they are living off of private investments. The proper way to target these people for additional funds is to nudge up the marginal tax rate on those private investments. This is difficult to accomplish, of course, because people with lots of money can afford to buy votes.

Also the age at which they might crash the market when they're all forced to begin dumping their 401(k) and IRA holdings. Kiyosaki called this "Rich Dad's Prophecy".